Microsurgery in periodontics and oral implantology: a systematic review of current clinical applications and outcomes.

OBJECTIVES: The aim of this systematic review was to comprehensively explore the current trends and therapeutic approaches in which an operating microscope (OM) is used in periodontics and dental implant surgeries. MATERIALS AND METHODS: A systematic search strategy was built to detect studies including various surgical techniques performed under an OM. PubMed, EMBASE, and SCOPUS databases were searched. No limitations in terms of time and language were applied. The data regarding the study design, type of procedure, treatment groups, and surgical outcomes were collected and analyzed descriptively. In addition, a bibliometric analysis was performed concerning the co-authorship and keyword co-occurrence network. RESULTS: Out of 1985 articles, finally, 55 met the inclusion criteria. Current periodontal and implant microsurgery trends consist of: periodontal therapy, dental implant microsurgery, soft tissue grafting and periodontal plastic surgery, bone augmentation, ridge preservation, and ortho-perio microsurgery. The bibliometric analysis revealed "guided tissue regeneration", "periodontal regeneration" and "root coverage" being the most repeated keywords (landmark nodes). 132 authors within 29 clusters were identified, publishing within the frameworks of "periodontal and implant microsurgery". CONCLUSION: Within its limitations, this systematic review provides an overview of the latest trends in periodontal and implant microsurgery when considering the use of an OM as the magnification tool. Also, it discusses the reported success and outcomes of the mentioned procedures.

Are Virtually Designed 3D Printed Surgical Splints Accurate Enough for Maxillary Reposition as an Intermediate Orthognathic Surgical Guide.

Background and Aim: The accuracy of the virtually-designed 3D-printed surgical splints requires investigation for the practical use of surgical plan in the operating room. This study aimed to compare the validity of the 3D-printed and the conventional intermediate splints and evaluate the outcomes after the surgical application of the 3D-printed splint compared with the predicted values. Methods: In this study, ten patients with dentofacial deformity were recruited. Participants were analyzed by the conventional surgical planning and virtual surgical planning. The intermediate surgical splints were created by the conventional and 3D-printing methods. Maxillary movements in 3 spatial directions were measured in an articulator after the application of both splints. Correlation and agreement between the two methods were tested by intraclass correlation coefficient (ICC). After the confirmation of 3D printed splint validity for each patient, the surgery was performed using 3D printed splints. It is assumed that ideally cephalometric prediction values are going to be obtained using conventional acrylic splints (gold standard). So, as a second objective, the outcome of the surgically-applied 3D-printed splint was evaluated and compared with the predicted values and finally analyzed by the paired t-test. Results: Based on the observations, there was an excellent agreement between the virtually-designed 3D-printed and conventional intermediate surgical splints (ICC ranged between 0.83 and 0.99 for linear values). There was a good cumulative agreement of ICC greater than 0.80. Overall, the mean linear measurements were not different between conventional and 3D-printed splint on the articulator. Also, there were no significant differences between the linear and angular measurements of 2D-cephalometric prediction and postoperation values. Conclusion: The results showed cautiously the acceptable accuracy of the 3D-printed splints for several parameters in three spatial dimensions within the laboratory and clinical settings.

Clinical efficacy of Vestibular Incision Subperiosteal Tunnel Access (VISTA) for treatment of multiple gingival recession defects: a systematic review, meta-analysis and meta-regression.

OBJECTIVES: This study investigated the efficacy of Vestibular Incision Subperiosteal Tunnel Access (VISTA) compared to other methods for treating multiple adjacent gingival recessions (MAGRs) through a systematic review and meta-analysis. MATERIALS AND METHODS: A systematic literature search was performed through June 2023, to identify clinical trials investigating VISTA for root coverage on MAGRs. A meta-analysis with meta-regression model was employed on the primary outcomes of mean and complete root coverages (MRC, CRC), comparing VISTA with other techniques. Clinical efficacy of various graft materials was assessed. RESULTS: Fourteen studies were included, 8 of which met the criteria for quantitative assessment. The cumulative MRC (88.15% ± 20.79%) and CRC (67.85% ± 21.72%) of VISTA were significantly higher compared to the tunneling technique (SMD = 0.83 (95% CI [0.36, 1.30], p < 0.01). The baseline recession depth showed a negative correlation with CRC, whereas baseline keratinized gingiva width exhibited a positive correlation with this outcome. CONCLUSIONS: The VISTA technique, particularly with acellular dermal matrix (ADM) or connective tissue graft (CTG) materials, offers superior outcomes compared to the tunneling technique. The capacity of platelet-rich fibrin (PRF) to substitute for connective tissue graft (CTG) in VISTA-root coverage was noteworthy, provided there is adequate keratinized tissue width. CLINICAL RELEVANCE: VISTA in concert with acellular dermal matrix or CTG resulted in improved root coverage, surpassing the outcomes achieved through tunneling. PRF emerged as a viable alternative to CTG, when used in conjunction with VISTA, demonstrating comparable mean root coverage. This is particularly evident in situations where sufficient keratinized gingiva is available and when patient comfort is taken into consideration.

Effects of lidocaine incorporation (without epinephrine) on pain and 2-week complications of botulinum toxin: a double-blind randomized placebo-controlled clinical trial.

No study has assessed the effects of the incorporation of isolated lidocaine into botulinum toxin for reducing its pain or complications. Studies on the dilution of botulinum toxin with other materials are as well extremely few, small, and limited methodologically. Therefore, we aimed to evaluate, for the first time, the effects of the incorporation of lidocaine alone into botulinum toxin type A on post-injection pain and complications. In this 2-week prospective, multicenter, double-blind randomized placebo-controlled clinical trial, 729 participants (667 females) were enrolled. They were randomized into placebo and lidocaine dilutions (about 2:1), and then into two brands of toxins (Dysport versus Xeomin). Hence, there were 4 subgroups. In the 2 experimental subgroups, botulinum toxin was diluted with 2% lidocaine without adrenaline; in the 2 control subgroups, botulinum toxin was diluted with normal saline as a placebo. After injection, the pain level was recorded (as an 11-scale numerical rating scale from 0 to 10). After 2 weeks, post-injection complications were assessed based on the participants' reports and the surgeon's observations. Data were analyzed using 3-way ANCOVA, multiple binary logistic regression, and bivariable analyses (α = 0.05, ß ≤ 0.1). The mean ± SD pain levels in the lidocaine group (n = 263) and the placebo group (n = 466) were 3.51 ± 2.04 and 4.15 ± 2.35, respectively. The mean ± SD pain levels in the subgroups 'Xeomin-Lidocaine (n = 61), Dysport-Lidocaine (n = 202), Xeomin-Placebo (n = 133), and Dysport-Placebo (n = 333)' were respectively 3.39 ± 1.86, 3.55 ± 2.09, 4.61 ± 2.49, and 3.97 ± 2.24. Lidocaine incorporation (P = 0.001), Dysport brand (P = 0.030), and younger age (P = 0.032) [but not sex (P = 0.406)] reduced pain. The only significant findings for 2-week complications were for the associations observed between aging with increased asymmetry (P = 0.022, OR = 1.032) and a need for a retouch (P = 0.039, OR = 1.021). Botulinum toxin dilution with lidocaine alone (without adrenaline or other ingredients) can reduce pain without affecting postinjection complications. Toxin brands may cause different extents of pain. Aging, but not sex, may increase pain. Two-week complications were not affected by any factors, except aging in the case of asymmetry and the need for a botulinum toxin retouch.

3-dimensional analysis of nasal soft tissue alterations following maxillary Lefort I advancement with and without impaction using 3D photogrammetry scanner.

PURPOSE: This study was designed to investigate the changes in nasal soft tissue following maxillary Lefort I advancement with and without impaction in subjects presenting a skeletal class III malocclusion, using a 3D photogrammetry scanner. MATERIALS AND METHODS: Patients with class III malocclusion undergoing Lefort I advancement with and without impaction and bilateral sagittal split osteotomy with the standard technique were included in this study. Patients were divided into two groups: maxillary Lefort I advancement alone (group 1) and combined with impaction (group 2). Facial soft tissue landmarks of the nose including nasal height (NH), nasal length (NL), nasal tip projection (NTP), alar width (AW), alar base width (ABW), subalar width (Sbal), nasolabial angle (NLA), nasofrontal angle (NFA), and columella inclination (CI) before and at least 4 months after surgery were obtained by a 3D scanner. RESULTS: Twenty-one patients were included in this study (Group 1: 11 and Group 2: 10). NH, NTP, and NL decreased significantly in both groups following surgery. In addition, Sbal decreased only in group 2. On the other hand, NLA and CI increased significantly in group 2. The inter-group comparison revealed a statistically significant difference in the alterations in NH, NL, and CI between the two groups. CONCLUSION: Changes in the nose soft tissue occurred after both surgeries, but their type and extent were different. Actions taken to reduce unwanted changes need to be further investigated. To evaluate the changes, 3D photogrammetry scan is a feasible imaging technique that can be used, providing numerous benefits.

Efficacy of hyaluronic acid, absorbable collagen sponge, and their combination in minimizing bisphosphonate-related osteonecrosis of the jaws (BRONJ) after dental extraction: a preliminary animal histomorphometric study.

INTRODUCTION: There is no study on the effectiveness of hyaluronic acid (HA) placement either with or without absorbable collagen sponge (ACS) in reducing or preventing bisphosphonate-related osteonecrosis of the jaws (BRONJ). This preliminary animal study examined the efficacy of this clinically important treatment. METHODS: For simulating BRONJ, zoledronic acid was administered to 40 rats for 5 weeks. Two weeks later, a right first molar was extracted from each rat. The rats were randomized into four groups of socket treatments: control (empty extraction socket) or with sockets filled with ACS, HA, or HA+ACS (n=4×10). After 2 weeks, 5 rats in each group were sacrificed and subjected to histopathologic and histomorphometric evaluation. Eight weeks post-surgically, the rest of rats were euthanized and histologically examined. The Kruskal-Wallis test was used to compare the four treatments at each time point (α=0.05). RESULTS: Six rats were lost overall. In the second week, vascularization was higher in ACS group (P<0.05); osteoclast activity was not different between groups (P>0.05); empty lacunae were the most and fewest in control and HA+ACS groups, respectively (P<0.05); eosinophil infiltration was maximum in HA group (P<0.05); lymphocyte counts were maximum and minimum in the HA+ACS and ACS groups, respectively (P<0.05); the highest and lowest neutrophil counts were seen in ACS and control groups, respectively (P<0.05); and the extent of live bone did not differ between groups (P>0.05). In the eighth week, vascularization was not different in groups (P>0.05); the highest and lowest osteoclast activities were seen in the control and HA+ACS groups, respectively (P<0.05); empty lacunae were the most and fewest in control and HA+ACS, respectively (P<0.05); maximum and minimum numbers of eosinophils were in control and HA+ACS groups, respectively (P<0.05); HA and control groups exhibited the highest and lowest lymphocyte counts, respectively (P<0.05); the lowest and highest neutrophil counts were observed in HA+ACs and control groups, respectively (P<0.05); and the highest and lowest extents of the live bone were observed in HA+ACS and control groups, respectively (P<0.05). CONCLUSIONS: Within the limitations of this preliminary animal study, HA and especially HA+ACS seem a proper method for preventing or treating BRONJ.

Three-dimensional assessment of airway volumes in patients with unilateral cleft lip and palate.

BACKGROUND: Considering the adverse consequences of respiratory insufficiency in cleft lip and palate (CLP) patients, this study aimed to assess the pharyngeal airway dimensions in 9-12-year-old patients with unilateral CLP. This historical cohort evaluated the cone-beam computed tomography (CBCT) scans of 30 patients with non-syndromic unilateral CLP between 9 and 12 years and 30 age- and sex-matched non-cleft controls. Three-dimensional (3D) images were reconstructed by the Mimics software, and the nasopharyngeal, oropharyngeal, and total airway volumes, as well as the minimal cross-sectional area of the airway (minAx), and posterior airway length (PAL) were all measured in the sagittal plane. Data were analyzed by the Student's t test. RESULTS: The oropharyngeal and the total airway volumes, as well as the minAx and PAL in CLP patients, were significantly smaller than the corresponding values in the control group (P < 0.05). Despite smaller nasopharyngeal airway volume in CLP patients than controls, this difference was not statistically significant (P > 0.05). CONCLUSIONS: Nine- to twelve-year-old non-syndromic unilateral CLP patients have smaller pharyngeal airway dimensions than non-cleft controls, and are therefore at higher risk of respiratory insufficiency.

Comparison of strengths of five internal fixation methods used after bilateral sagittal split ramus osteotomy: An in vitro study.

BACKGROUND: Results on the strength and displacement of internal fixation methods for bilateral sagittal split ramus osteotomy are controversial, and some designs have not been adequately studied. Therefore, this study was conducted to compare techniques using bicortical or monocortical screws. MATERIALS AND METHODS: In this in vitro study, 35 sheep hemi-mandibles were randomly assigned to five groups of seven each: fixation using (1) a 13 × 2 screw, (2) two 13 × 2 screws (arranged vertically), (3) three 13 × 2 screws, (4) 1 plate with 4 holes and four monocortical screws, and (5) a Y-shaped plate and five monocortical screws. Specimens underwent vertical forces until failure. Breakage forces and displacements of groups were recorded and compared statistically. Using one-way analysis of variance (ANOVA) with a Tukey's post hoc test and Kruskal-Wallis test. Level of significance was predetermined as 0.05. RESULTS: Strengths of Groups 1-5 were, respectively, 14.43 ± 4.35, 28.00 ± 8.89, 28.29 ± 8.01, 29.43 ± 8.24, and 61.29 ± 12.38 N, respectively (P = 0.000, analysis of variance). The corresponding displacement extents were 7.98 ± 0.04, 7.85 ± 0.26, 8.00 ± 0.00, 7.35 ± 1.73, and 6.79 ± 2.03 mm (P = 0.298, Kruskal-Wallis test). CONCLUSION: Use of a single bicortical screw is the weakest method, while Y-shaped plates might provide the highest strength. Using two or three bicortical screws or 4-hole plates might deliver similar strengths.

Comparative study of impact of animal source on physical, structural, and biological properties of bone xenograft.

BACKGROUND: Due to the unique features of xenografts including large supply from donors, minimal risk of human disease transmission, and the lower cost of preparation and production compared to autografts and allografts, they are considered as attractive alternatives to traditional bone grafts. The animal source accessibility and production process have a direct correlation with the cost and quality of the final product. To evaluate whether the animal source of the bone has any effect on the physicochemical and histological properties of the final xenograft, three deproteinized bone grafts were prepared from sources that are easily available in Iran, including the bovine (DBB), camel (DCB), and ostrich (DOB). METHODS: In the current study, three bone substitute materials intended to serve as bone xenografts were derived from the cow, camel, and ostrich using the thermochemical processing procedure. The physicochemical properties, in vitro cytocompatibility and in vivo bone regeneration capability of the prepared deproteinized bone grafts, were assessed and compared with OCS-B as an approved product in the global market. RESULTS: The physical tests confirmed the hydroxyapatite nature of the final products. SEM and BET analysis showed morphological and structural differences between the products due to differences in the animal sources. In vitro studies showed the prepared deproteinized bone was free of processing chemicals and was biocompatible with mouse fibroblast and myoblast cell lines. In vivo studies revealed that the bone formation capability of the DBB, DCB, and DOB has no significant difference with one another and with OCS-B despite their structural differences. The DCB showed the highest graft residue after two month. No signs of immunogenicity were observed in the study groups compared to the blank group. CONCLUSION: DBB, DCB, and DOB may offer a favorable cell response and bone regeneration similar to those of commercial bovine bone material.

Nasal Framework Osteotomy: An Innovative Approach to Manage an Extremely Long Nose With Meningoencephalocele.

Meningoencephlocele is a relatively rare deformity, usually characterized by penetration of brain or meningeal tissues through a defect in skull. This protruding tissue may affect facial structure and subtle to severe facial deformities may appear. Surgical treatments of these deformities are usually done by a team including a neurosurgeon and craniofacial surgeon. The conventional treatments includes several complicated operations to relocate herniating tissues, then correcting malformed facial structure. The nasal framework osteotomy, is an innovative approach that uses transfacial incisions to gain access to herniating tissue. Then, by completing the osteotomy around the nose, the entire nasal structure is lifted and transposed to it is original position. The authors believe that this technique may considerably reduce the complexity and risks of conventional approaches, while aesthetic demands are readily achieved at the same stage.

Efficacy of Photodynamic Therapy in Minimizing Bisphosphonate-Related Osteonecrosis of the Jaws After Dental Extraction: A Preliminary Animal Study.

PURPOSE: Except for a few case reports, there is no study on the efficacy of photodynamic therapy (PDT) in decreasing or preventing bisphosphonate-related osteonecrosis of the jaws (BRONJ). This preliminary animal study assessed the effectiveness of this clinical treatment. MATERIALS AND METHODS: Zoledronic acid was administered to 20 rats for 5 weeks. Two weeks later, a first molar was extracted from each rat. The rats were randomized to control and PDT groups. PDT was performed in the experimental group after surgery and at weeks 1, 2, 3, 4, 5, 6, and 7 after surgery. In the 8th week, BRONJ signs were evaluated by an observer blinded to randomization. Rats were euthanized and underwent histopathologic and histomorphometric evaluations. Clinical signs were compared using the Fisher test. Histomorphometric parameters were compared using the Mann-Whitney U test (α = 0.05). RESULTS: Two rats were lost from each group. Bone exposure decreased from 7 rats in the control group to 1 rat in the PDT group (P = .010). The stage of BRONJ decreased significantly from 7 rats in stage 1 to only 1 rat in stage 1 (P = .010). PDT decreased inflammation considerably for gingival eosinophils and lymphocytes and bone neutrophils, eosinophils, and lymphocytes. A larger percentage of live bone and smaller percentages of necrotic bone, empty lacunae, and neovascularization were observed in the PDT group. PDT also maintained bone remodeling, indicated by a large number of osteoclasts (P ≤ .001 for all comparisons by Mann-Whitney U test). CONCLUSIONS: Within the limitation of this preliminary animal study, PDT was found to be considerably effective clinically and histopathologically in decreasing or preventing BRONJ in rats. Future human studies are needed to verify these results.

Scleral exposure alterations following Le Fort I osteotomy (with and without maxillary impaction) in skeletal class III patients: A before-and-after clinical trial.

PURPOSE: Exposure of sclera below the iris in natural head positions is aesthetically undesirable. Studies on post-surgical changes in inferior scleral exposure following orthognathic surgery are scarce and mostly retrospective. The aim of this clinical trial is to examine the effect of Le Fort I osteotomy, a procedure for correction of malocclusion and maxillo-mandibular deformities, on the inferior scleral exposure and overall scleral surface area in skeletal class III patients. MATERIALS AND METHODS: This trial was performed on 40 eyes of 20 skeletal class III patients undergoing Le Fort I osteotomy without impaction (n = 20 eyes) and with impaction (n = 20 eyes). Standard true-size frontal photography was performed pre-operatively and post-operatively at 6 months. After measuring the overall eye height and the height of visible inferior sclera, the ratio of inferior sclera to overall eye height (S:E) was calculated three times. Also, overall surface area of the sclera was measured three times. The average of three attempts was considered the main measurement. Changes in the sclera after the surgery and between both methods were compared. RESULTS: The average age of patients (9 men, 11 women) was 24.5 years. Age and gender were balanced between the two groups (P > 0.05). S:E ratios decreased in both groups after surgery (P < 0.05, Wilcoxon test). The decrease was greater in the impaction group (P < 0.05, Mann-Whitney test). Similar results were observed for overall sclera surface areas. CONCLUSION: Maxillary advancement, with or without impaction, reduced the inferior scleral exposure and overall scleral surface area. The effect was more pronounced in the impaction group.

Family history and risk factors for cleft lip and palate patients and their associated anomalies.

BACKGROUND AND AIMS: Several environmental and genetic issues have been suspected as risk factors for oral clefts; and many studies have been conducted in this regard; however, large socioeconomic impacts of cleft lip and or palate (CL/P) justifies the need for further multifactorial researches. Current study aimed to assess parental risk factors for CL/P and its associated malformations. MATERIAL AND METHODS: Hospital records of 187 consecutive syndromic and non-syndromic children with cleft lip and or palate (103 boys and 84 girls) with a mean age of 1.7 (SD 2.2) years and 190 consecutive non-cleft children (103 boys and 87 girls) with a mean age of 2.8 (SD 2.2) years formed this study. Parental risk factors and abnormalities and physical problems and anomalies were evaluated in all subjects. RESULTS: Family history of clefts (OR 7.4; 95% CI), folic acid consumption (OR 7.3; 95% CI) and consanguineous marriage (OR 3.2; 95% CI) were quite strongly associated with increased risk of CL/P. In addition, all congenital abnormalities and physical problems had significantly higher incidence in CL/P patients. CONCLUSIONS: The findings of this study suggest that expecting mothers of consanguineous marriage and families with a history of CL/P should be extra cautious about the occurrence of CL/P.

Articaine (4%) with epinephrine (1:100,000 or 1:200,000) in inferior alveolar nerve block: Effects on the vital signs and onset, and duration of anesthesia.

BACKGROUND: This prospective, randomized, double-blind, clinical study was conducted to compare the effects of 4% articaine with 1:100,000 epinephrine (A100) and 4% articaine with 1:200,000 epinephrine (A200) on the vital signs and onset and duration of anesthesia in an inferior alveolar nerve block (IANB). METHODS: In the first appointment, an IANB was performed by injecting A100 or A200 in 1 side of the mouth (right or left) randomly in patients referred for extraction of both their first mandibular molars. In the second appointment, the protocol was repeated and the other anesthetic solution was injected in the side that had not received the block in the previous session. Systolic and diastolic blood pressures (SBP and DBP) and pulse rate were measured during and 5 min after the injection. The onset and duration of anesthesia were also evaluated. Data were analyzed using t-test and Mann-Whitney U-test, and p-value was set at 0.05. RESULTS: SBP and pulse rate changes were slightly more with A100; however, DBP changes were more with A200, although the differences were not significant (P > 0.05). There were no statistically significant differences in the parameters evaluated in this study. The onset and duration of anesthesia, and the changes in SBP, DBP, and pulse rate during and 5 min after the injection were the same in both the groups. CONCLUSIONS: For an IANB, A200 and A100 were equally efficient and successful in producing the block. Epinephrine concentration did not influence the effects of 4% articaine.

The effect of adding fentanyl to epinephrine-containing lidocaine on the anesthesia of maxillary teeth with irreversible pulpitis: a randomized clinical trial.

INTRODUCTION: Deep and long-lasting anesthesia is essential throughout endodontic treatment. This study was conducted to compare the effect of adding fentanyl to epinephrine-containing lidocaine on depth and duration of local anesthesia in painful maxillary molars with irreversible pulpitis (IRP). METHODS AND MATERIALS: This randomized double-blind, clinical trial with parallel design was conducted on 61 healthy volunteers; the control group received a mixture of normal saline and 2% lidocaine with 1:80000 epinephrine and the experimental group received a mixture of fentanyl and 2% lidocaine with 1:80000 epinephrine. The depth and duration of pulpal anesthesia were evaluated by means of electric pulp testing in 5-min intervals during a period of 60 min. Pain intensity was recorded five times: before injection, after injection, during access cavity preparation, initial file placement and pulpectomy using visual analog scale (VAS). All data were analyzed and compared using the chi-square and Mann-Whitney tests. RESULTS: Except for one patient in the control group, all others had deep and long-lasting anesthesia. The difference between pain intensity of the control and experimental groups was not statistically significant (P>0.05). CONCLUSION: Addition of fentanyl to conventional local anesthetic solution did not increase the effectiveness of infiltration in patients diagnosed with IRP.

Platelet-Rich Plasma in Treatment of Zoledronic Acid-Induced Bisphosphonate-related Osteonecrosis of the Jaws.

BACKGROUND: Bisphosphonate-related osteonecrosis of the jaws (BRONJ) is a well-known challenging entity warranting management. Platelet-Rich Plasma (PRP) plays an important role in bone biology by enhancing bone repair and regeneration. OBJECTIVES: The aim of this animal study was to evaluate the effects of PRP on zoledronic acid-induced BRONJ. MATERIALS AND METHODS: Seven rats were given 0.04 mg Zoledronic acid intravenously once a week for five weeks. Two weeks later, the animals underwent extraction of their first lower molars, bilaterally. After clinical confirmation of the osteonecrosis, PRP was injected randomly into one of the extraction sockets of each rat. Three weeks later, all rats were sacrificed in order to obtain histological sections. The analysis of epithelialization was performed by McNamar's test, and the analysis of osteogenesis and angiogenesis was performed by the Wilcoxon Sign Rank test. P value was set at 0.05. RESULTS: We found no significant differences between the two groups regarding the amount of epithelialization, angiogenesis or sequestrum formation (P > 0.05), but a significant difference was seen between the two groups regarding the amount of existing vital bone (P < 0.05). CONCLUSIONS: Our study demonstrates positive results (preservation or regeneration of bone) using PRP in treatment of BRONJ. Although PRP may enhance osseous regeneration, long-term follow-ups are required to confirm its benefits.

Analysis of stress distribution on fixation of bilateral sagittal split ramus osteotomy with resorbable plates and screws using the finite-element method.

PURPOSE: To determine the most appropriate stress distribution in fixation with resorbable screws and plates after bilateral sagittal split ramus osteotomy using the finite-element method. MATERIALS AND METHODS: This experimental study was performed on simulated human mandibles using computer software. The osteotomy line was applied to the simulated model and experimental loads of 75, 135, and 600 N were exerted on the model in accordance with the vector of occlusal force. The distribution pattern of stress was assessed and compared in 8 fixation methods: 1 resorbable screw, 2 resorbable screws in a vertical pattern, 2 resorbable screws in a horizontal pattern, 3 resorbable screws in an L pattern, 3 resorbable screws in a backward-L pattern, 1 miniplate with 2 screws, 1 miniplate with 4 screws, and 2 parallel miniplates with 4 screws each. RESULTS: Among the simulated fixations, 2 parallel miniplates showed the greatest primary stability and the single screw and the 2-hole miniplate showed the least tolerance to posterior forces. CONCLUSIONS: This study showed the 2-miniplate/4-hole plate pattern was the strongest and the single-screw and 2-hole plate patterns were the weakest of fixations in this bilateral sagittal split ramus osteotomy model. The finite-element method showed that polymer-based resorbable screws and plates (polyglycolic acid and d,l-polylactide acid) provide satisfactory primary stability in this model.

Biomechanical stress distribution on fixation screws used in bilateral sagittal split ramus osteotomy: assessment of 9 methods via finite element method.

PURPOSE: The aim of this study was to assess the biomechanical stress tolerance of screws used in 9 fixation methods after bilateral sagittal split ramus osteotomy to determine which configuration leads to lesser force load on the cortical bone at fixation points. MATERIALS AND METHODS: A 3-dimensional computerized model of a human mandible with posterior teeth was generated. The bilateral sagittal split ramus osteotomy was virtually performed on this model. The separated model was assembled with 9 fixation methods: single screw, 2 screws one behind the other, 2 screws one below the other, 3 screws in an L configuration, 3 screws in an inverted backward L configuration, miniplate with 2 screws, miniplate with 4 screws, 2 parallel plates (upper + lower border), and square miniplate with 4 screws. Then, 75-, 135-, and 600-N vertical loads were applied on the posterior teeth of these models. The stress distribution on the screw sites on the buccal cortex was measured by the finite element method. RESULTS: In this model all the fixation methods withstood forces between 75 and 135 N. However, the single-screw and the 2-hole miniplate models showed that the stress distributions in the configurations were intolerable when 600 N of posterior force was applied. The results of this study indicated that the inverted backward L configuration with 3 bicortical screws was the most stable. CONCLUSION: Although this study indicated that the inverted backward L configuration with 3 bicortical screws was the most stable pattern, most of the patterns had adequate stability for clinical applications (mean, 125 N).

Trigeminocardiac reflex during Le Fort I osteotomy: a case-crossover study.

OBJECTIVE: The present study aimed to assess the occurrence of trigeminocardiac reflex (TCR) during Le Fort I osteotomies. STUDY DESIGN: This case-crossover study included 25 Le Fort I osteotomy candidates without systemically compromising conditions. Mean arterial blood pressure and pulse rate values were recorded before downfracture (DF) (MABP1, PR1), during DF (MABP2, PR2), and after DF (MABP3, PR3). The data were analyzed using repeated measure ANOVA tests (alpha = 0.05). RESULTS: PR1 and PR3 were significantly higher than PR2 (P < .001). MABP2 value was significantly lower compared with MABP1 and MABP3 values (P < .001). PR2 and MABP2 showed a mean decrease of 6.5% and 9.7% compared with PR1 and MABP1, respectively. CONCLUSION: Different values have been suggested for TCR. Considering the limitations, the present study may suggest a revision of the values or descriptions for TCR, at least in maxillofacial Le Fort I osteotomy.